One of the more time consuming jobs in the construction and restoration fields is the setting (i.e. installing, leveling, and plumbing) of closures assemblies such as doors, windows, side lights, transoms, gable air vents, portals, skylights, etc., in rough structural openings. The rough opening is typically slightly larger than the closure assembly to facilitate installation.
Installers typically use wooden shims placed and sometime driven in the gap between the closure frame or jamb and the wall studs that form the rough opening. A level is used during this process to confirm the positioning of the jamb in the opening and re-adjustment of the shims is made as necessary to complete the installing, leveling and plumbing process. Levels are used on closures that have a flat vertical or horizontal side or sides. A plumb line is used on closures where a level is ineffective, such as a circular or oval closure.
Although the wooden shim is still the dominant means today for installing closures, it does have some limitations including: (1) the method of installing with wood shims is very time consuming; (2) wood shims are difficult to use on rounded surfaces (i.e. circular, oval-portals, stained glass ovals, etc.); (3) wood shims often interfere with complete sealing of the window to the rough opening; and (4) wood shims can slip out of place during installation of the closure assembly.
A gap is typically maintained between the closure assembly and the rough opening to accommodate expansion and contraction of building materials throughout temperature changes, as well as overall shifting and settling of the structure. Water, such as airborne moisture and liquid water in the form of rainwater, ice, snow can penetrate into the building wall interior from in and around building closure assemblies.
Attempts have been made to prevent entry of water into the building wall interior by sealing or caulking entry points in and around closure assemblies as the primary defense against water intrusion, or by installing flashing around the closure assemblies to divert the water. These attempts have not been completely successful. Sealants are not only difficult and costly to properly install, but tend to separate from the closure assembly or wall due to climatic conditions, building movement, the surface type, or chemical reactions. Flashing is also difficult to install and may tend to hold the water against the closure assembly, accelerating the decay.
The efficiency of such weatherproofing relies largely on the careful installation of both the closure assembly and the weatherproofing materials. However, no matter how carefully installed, moisture may enter into gaps between the closure assembly and the rough opening. Moisture penetration may be due to shifting or expansion/contraction of materials post-installation.
Such moisture typically collects below the closure assembly, where it can cause rot and other undesirable damage to both the closure assembly and the structure below the closure assembly. In some situations attempts to prevent water penetration around closure assemblies may actually trap the water within the structure, exacerbating the problem.
Various drain holes systems for closure assemblies have been used to divert water from the structure, such as disclosed in U.S. Pat. Nos. 3,851,420 (Tibbetts); 4,691,487 (Kessler); and 5,890,331 (Hope).
Specialized flashing structures have been developed for installation in the gap between the rough opening and the closure assembly. Examples of such specialized flashing structures are shown in U.S. Pat. Nos. 4,555,882 (Moffitt et al.); 5,542,217 (Larivee); and 6,098,343 (Brown et al.). U.S. Pat. Nos. 5,822,933 (Burroughs et al.) and 5,921,038 (Burroughs et al.) disclose a water drainage system with an angled pan and a plurality of ribs that is located underneath a closure assembly.
These specialized flashing structures, however, do not effectively remove water from the interior of the structure. Additionally, the installation of moisture guards often requires changes in the way the closure assembly is installed into the rough opening and how the closure assembly is finished on the room side so as to accommodate the vertical height of the angled pan. Furthermore, the gap between the closure assembly and the rough opening must be sufficient to accommodate the raised end of the angled pan.
The Installation Instructions for New Construction Vinyl Window with Integral Nailing Fin published by Jeld-Wen, Inc. discloses installing a 6″ tall section of screen to the exterior of the structure below the closure assembly. The screen extends about the width of the closure assembly and is located on top of flashing tape and building wrap. Another layer of flashing tape is applied to the top of the screen. The screen, however, forms one contiguous channel that is too large to permit effective drainage of water.